Variable back beam and method of allowing inflator to vary variable back beam in case of collision

A method of allowing an inflator to vary a variable back beam for a vehicle in case of collision with an object, the method comprising the steps of:

• sensing a collision of a left front or right front of the vehicle with the object;
• communicating between a power source of the vehicle and a squib by a trigger switch provided in an energy absorber;
• exploding powder filled in an inflator by electric power applied to the squib;
• and
• increasing a length of a beam positioned behind the energy absorber in a width direction of the vehicle by inflation pressure generated in the inflator;
• wherein the beam comprises a main beam connected to a crush box and an inner beam inserted into each of both sides of the main beam, and
• wherein:
• the inner beam comprises a non-exposed part inserted into the main beam and an exposed part exposed out of the main beam, and
• the inner beam is bent at a boundary between the non-exposed part and the exposed part.